Illuminated Rocker Switch Voltage Conversion

Introduction: Illuminated Rocker Switch Voltage Conversion

I am working on building a electric drift trike and wanted a switch for the electronics. Unfortunately, most DC switches around 48V tend to be either costly or not at all what I wanted (meaning did not include an internal light). I had this illuminated blue rocker switch sitting around but it was designed for 125V for the internal light. In this instructable I will show how I changed the 125V light to a 48V LED AND re-assembled it without breaking anything :)

This is a short ible and hopefully someone may find it useful just to know they need not fear to pull one of these apart and that it can be tailored to any voltage desired.

Step 1: Breaking Before Making

The first step was just to figure out how to pull it apart so I could get at the internals. I found that using tweezers I was able to pry the top blue rocker out of the black case while also pushing in the side tabs (on the long edge side, the holes where the switch snaps into). Doing so caused the whole thing to spring apart on me, so I recommend you try to be more careful than I was!

Once I have all the pieces in front of me, I was able to match it to the datasheet (2nd pic). In the lower right of the datasheet image you can see that contacts 2 and 3 are where the light was connected. I cut out the 150k ohm resistor and the light and discarded them. The light will not did not work at the voltage I wanted anyways (it should have based on 125V through a 150kohm resistor though, not sure why it didn't). I swapped in a blue 1206 SMD LED (3.2-3.4V). I aimed to run 5mA through the LED (could have done more) so I grabbed a fresh 10k ohm resistor as well. You can design the switch to illuminate at whatever voltage you want, just match the resistor accordingly.

I would one leg of the resistor in a similar fashion to the way the leg was wrapped around the rocker before I cut it out. See pic 4 for clarification because it is too hard to describe. I then trimmed the other leg of the resistor very short. It would then be soldered to the LED. The leg that was trimmed off was then used as the other pin for the LED and was wrapped around the other end of the rocker (see pics).

Step 2: Re-assembly

After soldering in the LED and resistor and bending their wires around back to how it looked when I took it apart, it was time to put it all back together. The middle black spring was put back in the rocker in the central hole where it would press against the leg of the resistor. This spring will eventually press against the small metal piece we put into the bottom of the case (pic 5 and 6).

Then the blue rocker cover can be put back onto the rocker (pic 2).

Then the small metal piece (pic 5 and 6) can be slid into grooves (pic 6) in the center of the black bottom case. Carefully lower the rocker down while aligning the black spring over the tip of the small metal piece while simultaneously aligning the spring that stayed connected in the bottom case into the other hole on the rocker switch. Press shut firmly until the blue top snaps / locks into the holes on the black bottom case.

Done!

If you picked the same resistor value as me you can test it out with a 48V source to make sure it turns on. Notice that it isn't connected to the switching line but rather is powered externally over the 3rd pin to the common central pin. You can power the LED at any voltage you design it for, just make sure to match the resistor accordingly!

From pic 2 and pic 3, I think you totally miss the basic thing: "o"=openned circuit and "-"=closed circuit. Light on when the switch says openned circuit and light off when the symbol says closed circuit

Those pictures are indeed backwards :) I ended up opening it all again to take the rest of the pictures after I confirmed that it worked but accidentally flipped the blue top on the first couple pictures. But since they turned out better (since every picture in this ible was taken from a mini microscope camera hanging out my mouth) I left those as the pictures despite being backwards. Oops.

I always thought of it as a logic table (0 vs 1) but I like your mnemonic too :)

it's important to note that the switch is intended for 125-250vac too much current will melt the switch and possibly cause a fire hazard. would be best to use a relay with the correct ratings in conjunction with this switch.

Correct. As with all switches that is :) This one is good for at least 20A and I even tested it to 22A without any problems (surprisingly). As it stands now though, I'm only using it for 5mA :) And the light part of the switch is (almost) unrelated to the current rating for the actual switching.

Just to beat this part of the topic to death (hopefully) since it has little to do with the author's main topic, the voltage rating does have a lot to do with a switch's use since he mentioned 48 volts DC (I know he's not switching his motor's current in his project.) The switch's rating of 20A at 125-250vac is not relevant to switching 48 volts DC, because of the high current arcing that occurs at the contacts of the switch as they open and close. This is why high current DC switches are more expensive.

On AC the reversing phases will quickly "extinguish" this arc, but on DC the arc continues until the contacts come together tightly enough to stop the arcing. Over time, the switch contacts could very well fuse together or create such pitting on the surface that they no longer work as a switch or get so hot that things start melting around the contacts. Switching inductive motor windings accentuates this arcing problem.

Of course, the author is smart enough not to use this switch to control his motor current. He's controlling a relay or electronic switch at very little current and will see none of the above problems.

Applications for higher voltage and being ac tend to draw less current... Typically no more than 15 amps. DC applications put more strain on the contracts.. Also, motors peak current draw can exceed the switches ratings and melt the switch. Voltage and current are two separate but related things.

hi,excellent work-to answer your query as to why the original light didn't work on 48v dc i believe its a neon and i found the following -so perhaps 48v is to low ?

Standard brightness lamps are filled with a neon/argon gas mixture, and high brightness lamps are filled with pure neon gas. When a starting voltage (usually 55-110 volts AC, or 90-140 volts DC) is applied, the gas ionizes and starts to glow permitting a very small current to travel from one electrode to the other.

The lamp in the switch originally is a neon lamp. These used to be pretty widely used before LEDs were common. It's a tube filled with neon gas with 2 electrodes. You have to get the voltage over about 70 volts or so before then neon will ionize and begin to conduct (which is why it did nothing on 48 vdc), and you also have to have a resistor to limit the current. When driven with an AC voltage, the neon around both electrodes will glow. When driven with a DC voltage, the neon will only glow around the negative electrode. The most common ones have an orangish-red glow. By using a mixture of gasses, you could also get a blue glow (much less common). They also come in a green (or less commonly, white) variety where the inside of the glass tube is coated with phosphor. When the neon inside glows, it excites the phosphor and causes it to glow.